'''
Copyright (c) 2008, appengine-utilities project
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
conditions are met:
Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided with the distribution.
Neither the name of the appengine-utilities project nor the names of its contributors may be used to endorse or promote
products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
'''
import __main__

class Event(object):
    """
    Event is a simple publish/subscribe based event dispatcher. It sets itself to the __main__
    function. In order to use it, you must import it and __main__
    """
    def __init__(self):
        self.events = [] 

    def subscribe(self, event, callback, args = None):
        """
        This method will subscribe a callback function to an event name.
        """
        if not {"event": event, "callback": callback, "args": args, } in self.events:
            self.events.append({"event": event, "callback": callback, "args": args, })

    def unsubscribe(self, event, callback, args = None):
        """
        This method will unsubscribe a callback from an event.
        """
        if {"event": event, "callback": callback, "args": args, } in self.events:
            self.events.remove({"event": event, "callback": callback, "args": args, })

    def fireEvent(self, event = None):
        """
        This method is what a method uses to fire an event, initiating all registered callbacks
        """
        for e in self.events:
            if e["event"] == event:
                if type(e["args"]) == type([]):
                    e["callback"](*e["args"])
                elif type(e["args"]) == type({}):
                    e["callback"](**e["args"])
                elif e["args"] == None:
                    e["callback"]()
                else:
                    e["callback"](e["args"])
"""
Assign to the event class to __main__
"""
__main__.AEU_Events = Event()
